Bolster lift clamp



Aug. 19,1969 R. D. scHAEFFER... 3,451,794

I l BOLSTER LIFT CLAMP Filed oor. 1s. 1967 FIG.|

INVENTOR F|G.4 ROBERT D. SCHAEFFER m'- 852% www United States Patent O 3,461,794 BOLSTER LIFT CLAMP Robert Dale Schaeter, Canal Fulton, Ohio, assignor to E. W. Bliss Company, Canton, Ohio, a corporation of Delaware Filed Oct. 13, 1967, Ser. No. 675,194 Int. Cl. B30b 15/06; BZlj 13/00 U.S. Cl. 100-229 10 Claims ABSTRACT OF THE DISCLOSURE This invention relates to presses and, more particularly, to an improved mechanism for centering, lowering and clamping a movable bolster in position in a press bed.

Although the invention will be described with particular reference to a bolster usable in metal working presses, it is to be appreciated that the invention is capable to broader application and may be utilized wherever it is desired to locate and lower a wheeled carrier into engagement with a supporting surface.

It is common practice in the press art to provide metal working presses with wheeled die carries or bolsters which are utilized to move die sets into and out of the press. When holsters of this type are employed, the die set normally is positioned on the bolster or carrier While it is positioned externally of the press and the carrier, with the die set, is then rolled as a unit into the press to a Y position beneath the press ram. It is, of course, necessary to position the die carrier accurately beneath the press ram and it is also necessary that the carrier be locked in this position. Moreover, it is undesirable to employ the wheels of the carrier as the support for the die set during operation of the press and, for this reason, the normal practice has been to provide appropriate mechanisms whereby the wheels are in some manner retracted so that the carrier rests directly on the press bed thereby providing a firm foundation for the lower die during subsequent press operation.

`One of the common means heretofore employed for placing the carrier in engagement with the press bed has been to provide some form of mechanism which retracts the wheels of the carrier. Moreover, some form of clamping mechanism normally is employed to maintain the carrier in position beneath the press ram. The clamps may comprise nothing more than bolts which secure the bolster to the bed or other techniques such as hydraulically actuated clamps may be used. With any of these prior art arrangements for lowering, locating and clamping the carrier in position, a multiplicity of mechanisms operating individually were required to accomplish the desired function.

It is a primary object of this invention to provide a single unitary mechanism for simultaneously locating, lowering and clamping the bolster in the proper position on the press bed.

In accordance with the principles of this invention, there is provided a mechanism for lowering the bolster into engagement with the press bed while simultaneously lee clamping the bolster to the bed in the lower position. This mechanism includes a support for the bolster during the lowering operation and a pivoted arm which is cammed into clamping engagement with the bolster in response to relative movement between the bolster and the bed.

More specifically, this invention contemplates a mechanism for lowering, centering and clamping a Wheeled die carrier in relationship to a press bed which mechanism includes a pivoted arm for engagement in an arcuate groove provided in each wheel and a rail supporting the wheel during the lowering with the rail having a line contact with the Wheel. The pivoted arm normally clamps the wheel at a point directly opposite the point of contact between the wheel and the rail so that a force couple is produced on the wheel if the wheel is not properly positioned along the rail thereby causing the wheel to roll along the rail until the carrier is properly positioned.

In accordance with a more specic aspect of the invention there is provided a plurality of vertically movable pistons formed in the press lbed and alternately movable between a raised and lowered position by double acting hydraulic cylinders. Each of the pistons has a section of rail or track formed thereon which engage the Wheels of the die carrier or bolster. Each piston has a pair of 0pposed clamps adapted for engagement with arcuate grooves formed on opposite sides of each wheel of the carrier. Springs normally bias the opposed clamps away from each other so that the wheels of the carriers may move in between the two clamps. As the piston is retracted into the press bed, the two clamps co-act with the walls of the cylinder in which the pistons are received and are cammed into engagement with the arcuate grooves in each wheel thereby locking the carrier in position.

It is an object of this invention to provide a mechanism which simultaneously lowers, centers and clamps a Wheeled die carrier in position on a press bed.

Another object of this invention is to provide a clamping mechanism for a die carrier which mechanism accurately centers and holds the die carrier in position during press operation,

A further object of this invention is to provide a mechanism for quickly changing die sets in a press which mechanism is simple in construction, requires a minimum of manual manipulation and yet provides an arcuate means for positioning the die carrier in the press.

These and other objects will become apparent from the following description when read in connection with the accompanying drawings in which:

FIGURE 1 is a side elevation view of a portion of a press having an improved bolster lift clamp mechanism constructed in accordance With this invention.

FIGURE 2 is a sectional view taken along line 2-2 of FIGURE 1.

FIGURE 3 is a side elevation view of FIGURE 2. FIGURE 4 is a View similar to FIGURE 2 with the die carrier in the lowered and clamped position.

Referring now to the drawings wherein the showings are for the purpose of illustrating the preferred embodiment of the invention only and not for the purpose of limiting the same, FIGURE 1 shows the overall arrangement of a metal working press A provided with a movable bolster assembly B. The press A is shown as a relatively conventional metal working press comprised of a bed 10 having an upwardly facing surface 11 and four vertically extending uprights 12. A ram 14 is carried by the uprights for vertical movement toward and away from the bed 10. The press further includes the usual drive mechanism for driving the ram 14 as will be understood by those having skill in this art.

The die carrier or movable bolster assembly B includes a relatively conventional carrier 20 comprised 0f a frame 21 having an upper horizontal surface 22 and a generally parallel horizontal lower surface 23. The car rier is provided with four wheels 25 mounted generally at each corner of the frame 21 on axles 25a with the wheels being adapted to support the carrier for guided movement along tracks or guide rails 26 which extend from a position outside the press into and across the press bed. The tracks or rails may `be of any type of construction but as shown comprise a track or rail 27 in a groove 28.

The arrangement thus far described is relatively conventional and facilitates moving die sets into and out of the press. As shown in FIGURE 1, with the carrier 20 positioned outside the press, a die set including upper and lower die halves 28a and 28b can be positioned on the upwardly facing surface 22 of the carrier. Normally, the lower die half 28b is positively connected to the carrier by appropriate means such as bolts. The carrier is then rolled into the press to a position beneath the ram 14 as shown in solid lines in FIGURE 1. With the carrier in position under the ram, the ram is moved downward- 1y into engagement with the top surface of the upper die half 28a and, by appropriate means, connected thereto. To change die sets, the above sequence of Operations is reversed and the die set the carrier rolled out of the press and a second die set brought in.

IPrior to operation of the press, it is necessary that the carrier or bolster be securely positioned on the press bed. This is accomplished by a plurality of die carrier lowering and clamping mechanisms, one of which is illustrated in FIGURE 2 and indicated generally by the reference numeral 40. One such clamping and lowering mechanism 40 is provided for each of the wheels 25 and each mechanism is located in the press bed at a position which corresponds to the desired location of the wheels of the die carrier on the press bed when the press is to be operated.

Referring more specifically to FIGURE 2, each lowering and clamping mechanism comprises a cylinder housing 42 which is located in an aperture 44 formed in the bed of the press. The cylinder housing includes a central bore 46 in which there is received a slidable piston 48. The piston is connected by a piston rod 50 to a double acting hydraulic cylinder 52.

T'he piston 48 includes a vertically extending transverse slot 54 in which there are received a pair of clamping arms 56, 57 pivotally supported by pivot pins 58, 59 respectively. Each of the clamping arms 56, 57 projects upwardly from the slot 54 above the level of the press bed 10 and includes at their upper ends inwardly directed nose portions 60, 61, respectively.

The opposed side walls of the slot 54 in the piston 48 include outwardly diverging cam slots 62, 64. A biasing means in the form of a rod 65 and spring 66 are disposed between the opposed inner surfaces of the clamping arms 56, 57 and normally bias the clamping arms to a position wherein they are in engagement with the cam slots 62, 64. This relationship is illustrated in FIGURE 2.

The piston 48 further includes at its upper surface, a portion of the track 27 on which the die carrier Wheels 25 are adapted to roll. As is apparent from FIGURE 2, the wheel 25 has a track engaging surface 68 and a locating flange 70 which is adapted to engage the side of the track 27 and maintain the wheel in position on the track 27. In addition, each die carrier wheel 25 further includes an arcuate groove 72 formed on opposed sides thereof with the configuration of the groove being such that the nose portions 60, 61 of the clamping arms 56, 57 may be received therein. Moreover, the nose portions 60, 61 are designed to engage the outer wall of the grooves 72 when the wheel is properly positioned thereby to securely restrain any movement of the carrier.

The entire mechanism 40 is adapted to be reciprocated vertically through action of the hydraulic cylinder 52 or such other means as may be appropriate. It will be appreciated that as the piston 48 is moved downward, as

viewed in FIGURE 2, the track section 27 on the upper surface of the piston is also retracted within the cylinder bore 46 and thereby lowered beneath the upper surface 11 of the press bed 10. Moreover, as the piston 48 is lowered, the clamping arms 56, 57 co-act with the inner terminal portions of cam slots 62, 64 and are pivoted about their respective pivot pins 58, 59' inwardly of the cylinder to the position shown in FIGURE 4.

The mechanism 40 functions to locate, lower, and clamp the die carrier in the press bed in the following manner. The die carrier assembly B is moved along the rails 27 to a position beneath the ram 14. In this position, the wheels 25 are each located over one of the assemblies 40 and the relationship of the parts is as illustrated in FIGURE 2. Thereupon, the hydraulic cylinders 52 are simultaneously actuated to retract the piston 48 within the cylinder housing 42. As the piston 48 is retracted the die carrier B, which is resting solely upon the sections of track 27 which are carried on the pistons 48, is also lowered until the lower 4surface 23 of the die carrier frame rests on the press bed 10. As the piston 48 is being lowered, the clamping arms 56, 57 co-act with the cam slots 62, 64 in the manner above described and are pivoted against the bias of the spring 66 to a position substantially vertical, as shown in FIGURE 4. As the arms 56, 57 assume a vertical position, the nose portions 60, 61 respectively of the two arms enter the annular grooves 72 on opposite sides of the -wheels 25 to clamp the wheels` in position on the track section 27.

In the event that the die carrier is not precisely located beneath the ram 14, the nose portions of the clamping arms 56, 57 will engage the walls of the annular grooves 72 and provide a camming force which will tend to move the die carriers longitudinally along the track until the nose portions of the arms can freely enter the groove 72. This camming action on the wheeels 25 serves as a centering operation and results from the coincidence of the line of engagement between the lower surface of the nose portion and the radially outer wall of the groove 72 with the line of contact between the wheel and the track. Thus, referring to FIGURE 3, the line of contact between the wheel 25 and the track 27 is indicated by the arrow 75. Similarly the line of contact between the nose portion 61 and the corresponding groove 72 in the wheel 25 when the wheel is properly positioned is indicated by the arrow 76. Thus, when the die carrier is properly positioned in the press bed, the arrows 75, 76 are in vertical alignment and coincide with the vertical axis 77 through the wheel axle 25a. If the carrier is not properly positioned, the nose portion of the clamping arm will engage the wall of the groove 72 at a point removed from the vertical axis 77 which will result in the development of a moment of force causing the wheel 25 to rotate about axle 25a until the proper position of the die carrier has been achieved and the nose portions are free to enter fully into grooves 72. Thereafter, the carrier remains locked in position and the press may be operated in conventional manner.

To release the carrier, the cylinders 52 are actuated to move pistons 4S to an elevated position wherein the track sections on the pistons are aligned with the track 27 on the bed 10. As the piston moves upward, the spring 66 biases the clamp arms 56, 57 apart thereby releasing the carrier for movement.

Having thus described my invention, I claim:

1. In a press having a bed with an upwardly facing surface, a ram movable toward and away from said bed surface, a carrier having wheels on which the carrier is supported for movement, and guide track means formed in the press bed adapted to cooperate with the carrier wheels, said guide track means extending from a position outside the press to a position within the press and beneath the ram, the improvement comprising:

means on said bed cooperating with said carrier wheels for simultaneously lowering said carrier from a bed disengaged position to a bed engaged position and engaging said wheels to clamp said die carrier to said bed in said bed engaged position.

2. The improvement of claim 1, wherein said lowering means comprises vertically reciprocable piston means in the press bed in engagement with each of said carrier wheels when the carrier is positioned beneath the ram;

means for reciprocating said piston means for raising and lowering the die carrier, and

clamp means mounted on said piston means for clamping said wheel of said carrier to said piston means as said piston means is moved to a lowered position.

3. The improvement of claim 2, wherein said clamp means comprises a vertically extending clamp arm with the upper end of said arm being positioned above said press bed, when said piston means is in its raised position,

means pivotally supporting said arm for movement toward and away from said guide track, and

cam means on said press bed cooperating with said arm to move said arm toward said guide track as said piston is retracted.

4. The improvement of claim 3, wherein each of said carrier wheels includes an annular groove formed therein,

said clamp arm including a nose portion adapted to be received in said annular groove.

5. The improvement of claim 4, wherein a pair of annular grooves are formed on opposite sides of said wheels and each piston includes a pair of pivotally mounted clamping arms adapted to be received in the grooves.

`6. The improvement of claim 2, wherein said clamp means engages said -wheel at a point in vertical alignment with the point of contact between said wheel and said piston means when said carrier is properly positioned beneath the ram.

7. The improvement of claim 1, wherein said lowering and clamping means comprises cylinders received in apertures in the press bed with the number of said cylinders corresponding to the number of wheels on said carrier,

a piston in each of said cylinders,

an upwardly opening slot formed in each piston,

clamp arm means pivotally disposed in each slot and projecting above the piston,

guide track means on said piston, and

means cooperating with said clamp arm means for pivoting said clamp arm means toward and away from said guide track means on said piston.

8. The improvement of claim 7, wherein said cooperating means comprises cam means on said press adjacent said clamp arm means, and

biasing means normally biasing said clamp arm means into engagement with said cam means.

9. The improvement of claim 7, wherein said carrier wheels include an annular groove formed therein,

said clamp arm means including a nose portion adapted to be received in said annular groove.

10. 4In a press having a bed with an upwardly facing surface, a ram movable toward and away from said bed surface, a carrier having wheels on which the carrier is supported for movement, and guide track means formed in the press bed adapted to cooperate with the carrier wheels, said guide track means extending from a position outside the press to a position within the press and beneath the ram, the improvement comprising:

lowering means comprising vertically reciprocable piston means in the press bed adapted to engage the carrier wheels when the carrier is positioned beneath the ram,

means for reciprocating said piston means for raising and lowering the die carrier,

clamp means movably mounted on said piston means,

said clamp means having a portion thereof extending above the press bed when said piston means is in its raised position, and,

means cooperating with said clamp means for moving said clamp means transverse to said guide track means and into engagement with said carrier as said piston means is lowered whereby said carrier is clamped to said press bed.

References Cited UNITED STATES PATENTS 2,996,025 8/ 1961 Georgei 72-446 3,002,479 10/ 1961 Johansen et al 72-412 3,134,350 5/1964 Danly et al 72-416 3,225,686 12/ 1965 Clements 1GO-229 XR 3,229,791 1/ 1966 Soman 100--229 XR BILLY J. WTLHITE, Primary Examiner U.S. C1. X.R. 72-446, 448 

